Peptides are natural products, protein fragments, consisting of at least two amino acids and have the ability to regulate some physiological processes: immunity, defense, growth, reproduction. In dermatology and cosmetics their use concerns the correct development of pigmentation, the contrast to inflammation and, in the component of the extracellular matrix, they are signal modulators. They have antibiotic, hormonal and neurotransmitter properties so they are used for wound healing, antimicrobial defense, angiogenesis, skin defense as they can disrupt bacterial membranes.

Interesting as a therapeutic modality, however, they are, in principle, impermeable to the cell membrane and, in vivo, susceptible to proteolytic degradation.

Peptides are found in the human organism, wasp venom¹, plants, etc.

There are approximately 13,000 natural peptide molecules that are generally divided into 

• Short linear ( ≤ 10 residues, unmodified linear peptides are highly unstable²) have low binding affinity and poor resistance to proteolytic degradation. They can be used to develop antibiotics. They exhibit antiviral activity³
• Cyclics (insulin, penicillin. gramicidin, cyclosporin), found in plant families such as Caryophyllaceae, Rutaceae and Linaceae. They are potential therapeutic agents useful in dermatology and cosmeceutical applications.⁴  

• Macrocyclic (carry one or more rings and cover multiple amino acid residues) are produced by non-ribosomal peptide synthetases or ribosome-derived peptides by post-translational enzymatic modifications The macrocyclization procedure enhances the pharmacological properties and bioactivity of the peptides. Macrocyclic peptides are preferred molecular modalities that can be used for diagnosis (e.g., biosensors, glucose sensors), disease treatment (e.g., antimicrobial, cancer therapy), and drug delivery⁵
• Cyclotides found in several plant families, have good amounts of disulfide, exhibit different biological properties. Structurally, cyclotides share a characteristic circular knotted head-tail topology of three disulfide bonds. This structure provides cyclotides with extraordinary resistance to thermal and chemical denaturation⁶. Recently, they have received attention for the treatment of Multiple Sclerosis.
• Circular, researched as scaffolds for drug design as they demonstrate protein-like properties in the context of small, bound peptides⁷
• Oligopeptides (about 10-20 amino acids) or polypeptides (more than 20 residues) are a group of low molecular weight, highly diverse peptides, and, within them, contain both proteinogenic and non-proteinogenic amino acids. They are used in dermatology. 

For better information I refer to this substantial study written by a large multidisciplinary group of leading scientists, academic and pharmaceutical experts from all continents of the world who provide an invaluable global perspective on short peptides towards biomedical innovations⁸.

Fish are a relatively recent source of bioactive peptides and proteins used by the pharmaceutical and cosmetic industries for the anti-aging, antimicrobial and antioxidant properties of the active ingredients. Peptides derived from the marine environment year a broad spectrum of bioactivities: antioxidant, antimicrobial, antihypertensive, calcium-binding and obesity-controlling⁹.

References___________________________________________________________________

(1) Lee SH, Baek JH, Yoon KA. Differential Properties of Venom Peptides and Proteins in Solitary vs. Social Hunting Wasps. Toxins (Basel). 2016 Jan 22;8(2):32. doi: 10.3390/toxins8020032.

(2) Zuconelli CR, Brock R, Adjobo-Hermans MJW. Linear Peptides in Intracellular Applications. Curr Med Chem. 2017;24(17):1862-1873. doi: 10.2174/0929867324666170508143523.

(3) Kozhikhova KV, Shilovskiy IP, Shatilov AA, Timofeeva AV, Turetskiy EA, Vishniakova LI, Nikolskii AA, Barvinskaya ED, Karthikeyan S, Smirnov VV, Kudlay DA, Andreev SM, Khaitov MR. Linear and dendrimeric antiviral peptides: design, chemical synthesis and activity against human respiratory syncytial virus. J Mater Chem B. 2020 Apr 1;8(13):2607-2617. doi: 10.1039/c9tb02485a.

(4) Namjoshi S, Benson HA. Cyclic peptides as potential therapeutic agents for skin disorders. Biopolymers. 2010;94(5):673-80. doi: 10.1002/bip.21476.

(5) Wang W, Khojasteh SC, Su D. Biosynthetic Strategies for Macrocyclic Peptides. Molecules. 2021 Jun 1;26(11):3338. doi: 10.3390/molecules26113338.

(6) Ojeda PG, Cardoso MH, Franco OL. Pharmaceutical applications of cyclotides. Drug Discov Today. 2019 Nov;24(11):2152-2161. doi: 10.1016/j.drudis.2019.09.010.

(7) Ongpipattanakul C, Nair SK. Biosynthetic Proteases That Catalyze the Macrocyclization of Ribosomally Synthesized Linear Peptides. Biochemistry. 2018 Jun 12;57(23):3201-3209. doi: 10.1021/acs.biochem.8b00114.

(8) Apostolopoulos V, Bojarska J, Chai TT, Elnagdy S, Kaczmarek K, Matsoukas J, New R, Parang K, Lopez OP, Parhiz H, Perera CO, Pickholz M, Remko M, Saviano M, Skwarczynski M, Tang Y, Wolf WM, Yoshiya T, Zabrocki J, Zielenkiewicz P, AlKhazindar M, Barriga V, Kelaidonis K, Sarasia EM, Toth I. A Global Review on Short Peptides: Frontiers and Perspectives. Molecules. 2021 Jan 15;26(2):430. doi: 10.3390/molecules26020430.

(9) Pangestuti R, Kim SK. Bioactive Peptide of Marine Origin for the Prevention and Treatment of Non-Communicable Diseases. Mar Drugs. 2017 Mar 9;15(3):67. doi: 10.3390/md15030067.